Smells are very evocative, and one certainly is more exposed to them cycling than in a car. In this age where the number of electric vehicles are growing and where almost all ICE vehicles have electronic engine management and other devices to meet emissions targets, every one in a while I'll encounter an old diesel truck or and old gansoline-fueled car running rich or lean. Those three smells immediately transport me back to my youth in the heavy traffic of Chicago of the 1960s and 70s. The population and traffic in Colorado Springs has grown so much in my 33 years here and yet, cycling in heavy traffic, or stuck in a standstill on the highway in the car, I rarely smell engine exhaust the way I used to as a kid...although I'll admit my sense of smell isn't what it used to be.